Questions tagged [digital-communications]
Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.
0
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2answers
33 views
1-wire differentiate read from write
I've been reading documentation on 1-wire and I think I'm having a brainfart. How does the slave differentiate a read slot from a write slot?
reference:
https://www.maximintegrated.com/en/app-notes/...
1
vote
0answers
33 views
How to Low-Pass PDM Output Data
I have a PDM-Mems Microphone which provides me with 101010 data, the Microphone has a Clock of 3Mhz. I read the manual about how PDM is generated, but I haven't worked with digital filters yet and in ...
-1
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1answer
24 views
Pairing vs Master-slave between BT Module to BT Module
If I take two identical BT modules, for example HC05 or HC06 then is it possible to pair the two modules with each other or is it like you need 1 master and 1 slave module for pairing?
Edit:
Now I ...
-1
votes
1answer
61 views
Bluetooth vs BT Beacon [on hold]
While trying to understand how BT devices work I came across another related term "BT Beacon". Is it same as BT communication or if a device is termed as BT beacon then it would have some specific ...
0
votes
0answers
44 views
What is the fieldbus for Unitronics PLC?
I am currently investigating the inner behavior of a PLC of the brand Unitronics. I identified several bus for the communication with actuators, other PLCs, etc (like Modbus or CANbus)
One thing I ...
0
votes
0answers
10 views
finding the minimal length of a broadcasting frame in a channel(CSMA/CD)
i am unsure about this question. would appreciate your assistance with it.
in the following CSMA/CD network with cable length L and propagation T. assuming that the signal is not decreasing and there'...
0
votes
1answer
43 views
Does direct GPIO communication between 2 microcontrollers requires pull up/down
If I want to use GPIO pins of two microcontrolles as a mean of simple communication (e.g. reporting an event by sending 1 or 0), Do I need to enable internal pull up or pull down resistors on any of ...
0
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0answers
67 views
Probing LPC bus with an FPGA yields gibberish — wiring problem?
I'm trying to repeat the TPM key dumping experiment by Pulse Security using a motherboard with Secure Boot and the same TPM1.2 chip onboard, equipped with Windows 8.
However, when I connect the FPGA ...
0
votes
1answer
57 views
Finding the overhead and distance of an unknown code based on message making algorithm
for an information word M with m bits that is coded as following:
M is coded into a word A using an unknown code that allows detection of not more than one error.
the code word is the word obtained ...
0
votes
1answer
15 views
loading multiple shift registers from few pins
We want to load two 32 bit data shift registers without concatenating them using 4 control lines (SI1, SI2 clock, latch). It can be done by bit banging but can it be done using SPIs using only 4 lines?...
0
votes
0answers
18 views
Find Bit Error Rate and Eb/N0?
I have read about Bit Error Rate and Eb/N0 to find out how can I generate them. I understand BER but what confused me is Eb/N0. How can I find Eb/N0 values and the corresponding BER values.
I have ...
1
vote
1answer
45 views
Signal placement in flat ribbon cable, FPC or FFC with digital and power signals
I want to interface different boards with FPC/FFC or ribbon cable and I was wondering about the placement of the signals in the cable.
I plan to have a 39 signals FPC with :
1 SPI bus (SCK, MOSI, ...
0
votes
1answer
53 views
Visualise a bit pattern
My objective is to send a bit pattern of 1000 bits from one microcontroller (PIC or Atmel) to another one using the SPI method.
How can I visualize the bit pattern so I can find the errors of ...
1
vote
1answer
34 views
Source generator for Satellite Tuner input
I need to design a source generator for a TV factory. They want to automatize the functional tests by applying a test module to the TV's at the end of the production line. All the peripherals of the ...
1
vote
1answer
43 views
What is the effect of redundancy coding on the bit error rate?
If I have a channel with bit error rate BER = \$10^{-3}\$ after modulation, but this is too high so I decide to add repetition coding. With 2 code words and block length of 3 such that I have a ...
0
votes
3answers
88 views
Choosing best bus and protocol for ~128 clients over the wire
I am up to design system with ~128 MCUs communicating to one MCU master. Communication will be bidirectional. Data will be mostly sensor reads, but I plan to use the bus also as communication method ...
0
votes
1answer
90 views
How do I stop signal looping with I/O port in this communication system
I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...
2
votes
3answers
95 views
How is companding different from pre-emphasis and de-emphasis?
What I know is that interference increases linearly with frequency and thus noise power is concentrated at higher frequency. So, to reduce noise, pre-emphasis and de-emphasis filters are used which ...
-1
votes
1answer
185 views
Signed and unsigned numbers in verilog
I understand the concept of fixed point and multiplying signed with unsigned by sign extension the unsigned number with 1 bit of '0' so it will be signed always positive number, But my question
If I ...
0
votes
1answer
79 views
UART Transmit issue in VHDL
I'm working on a UART transmit process (uart_transmit) in VHDL (115200 baud, 8 data bits, 1 stop bit and no parity). I need the transmit line ...
0
votes
1answer
112 views
Are horizontal and vertical back porches required for digital video, and if so, why?
The necessity of vertical and horizontal front and back porches in analog video seem fairly intuitive to me, but why are they necessary for digital video at all? In this LCD module data sheet and this ...
1
vote
1answer
76 views
In wireless communication, what is “channel length”?
In wireless communication, I am confused about what people are referring to when they use the term 'channel length.' Can someone explain the term or provide me a definition?
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0answers
61 views
High data rate (~1-5 Mpbs) Point to Point Radio
I'm working on a rocket project at my University, and am trying to find a point to point / point to multipoint radio capable of a hopefully 1-5 Mbps data rate between a ground station a directional ...
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votes
2answers
142 views
What device can convert (EEG) voltage data to real voltage? [closed]
I seek a device that can be programmed to output physical voltages based on a set of datapoints. For example:
...
0
votes
1answer
51 views
Inverse Z-transform Problem [closed]
I'm rather stuck trying to compute the inverse Z-transform y[n] of the function below. I'm having trouble selecting the correct formulas from the table to achieve the right solution.
Any help with ...
1
vote
1answer
65 views
Ringing issue on I2C FM+ bus between MCU and few sensors - Power supply issue?
I'm experiencing some issues while probing a problematic I2C bus on the oscilloscope.
We want to interface several TLV493D-A1B6, with a STM32L4 (we are working as well on STM32F4 and have the same ...
0
votes
3answers
49 views
Practical Limitations to 1-Wire Communication Speed [closed]
What are some practical limitations to the speed of a 1-Wire interface?
1
vote
2answers
144 views
Can someone explain the use of the transistor in this circuit?
I came across a schematic which implemented a 1 Wire interface. However, this 1-Wire interface circuit also includes a transistor connected as shown in the picture. Can somebody expain why this has ...
0
votes
5answers
113 views
RS485 IC Termination Resistor Configuration
I've made a mistake on a design, that went into production...
It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the ...
0
votes
0answers
57 views
Derivation of stability criterion for type 3 digital PLL
Could anyone help to derive the following expression (4.23) which is the stability criterion for type 3 digital PLL ?
Note: Screenshots are taken from Floyd Gardner's book : Phaselock Techniques 3rd ...
-1
votes
1answer
31 views
What are cost-effective and ways of providing global communication between two devices besides internet and SMS?
I am currently in the process of building a system which allows vehicles to send information back and forth with an Arduino. The main problem I am facing right now, is that the current implementation ...
1
vote
2answers
54 views
Geometric representation of GMSK signal
Can anyone provide me the geometric representation of GMSK signal? Also, am I correct in saying that bit energy of GMSK is same as its symbol energy since MSK is a binary modulation scheme with only ...
0
votes
1answer
54 views
Printer Data Cables with *suspected* IC boards [duplicate]
I've one found of those printer data cables that have some kind of pair integrated circuit along them, one at each end just before the plugs, I was wondering if there is a less invasive way of ...
0
votes
1answer
105 views
Asynchronous FIFO in clock domain crossing
Clock domain crossing issue can be solved by using asynchronus FIFO with input frequency f1 is of the source domain and f2 is of the destination frequency.
If the data is sent in bursts, depth can be ...
6
votes
2answers
174 views
Using optocouplers at the end of a twisted pair
I am designing a dumb "isolation box" that is to sit between a computer and medical data acquisition equipment. The purpose of this box is to inject power and to provide communications and digital ...
0
votes
1answer
56 views
How to know voltage used on a data bus?
How do you find out what voltage is being used on a data bus for the high signal?
On a small electronics I guess you can assume it will be 3.3v or 5v but what about other circuits, say in a car or on ...
0
votes
1answer
33 views
How can Erlang C values be greater than one?
Here is an Erlang C plot I did myself. The x-axis represents the total traffic while the y-axis represents the probability. Each line represents a different total number of channels.
As you can see, ...
1
vote
1answer
84 views
Why are Erlang B and Erlang C formulas different?
Erlang B determines the probability that a call is blocked and is defined as:
$$Pr[blocking]= {{A^C \over C!} \over {\sum_{k = 0}^{C} {A^k \over k!}}}$$
while Erlang C determines the probability ...
38
votes
10answers
12k views
Can a premium HDMI cable outperform a standard cable?
Assuming two cables both conform to the same standards (e.g. HDMI2.0, high-speed, ...) is it possible that a premium cable will outperform a standard cable when using an objective benchmark that ...
0
votes
1answer
17 views
dsb_sc of sin wave
Can we take the dsb_sc(Double side band suppressed carrier)of a sinusoidal signal I know that it exists for cosine but for sine I can't find anything on the internet
1
vote
1answer
124 views
Transmitter and Receiver antennas in mobile phones
I understand that in old cellular systems where FDD were employed, we used to have same antenna at the mobile phone (User equipment) for transmission and reception.Moreover, a duplexer was used to ...
1
vote
1answer
628 views
Analog beamforming vs digital beamforming
I am reading some research articles on wireless communication where they talk about beamforming techniques and their differences in Multiple antenna Tx-Rx systems (MIMO). It says analog beamforming ...
1
vote
2answers
47 views
Pulse Train Sampling Rate
Assume I have a pulse train with frequency of F Hertz. A normal square wave has all odd harmonics. From Nyquist, if I want to "Reconstruct" the waveform, sampling frequency Fs should be at least 2*(...
13
votes
7answers
5k views
Is it possible to send multiple data bits on a single wire at once?
Is there an existing protocol or modulation method where multiple data bits are sent over a single wire at once or maybe an additional ground line (like serial communication)?
I know there are ...
1
vote
0answers
52 views
How do I get the FSM table from the given diagram?
Given one is question and another solution. I cant come to this solution. can anyone help here
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votes
1answer
107 views
How do I get the sum and carry expression for ripple carry adder?
please check the photo and kindly let me know how to find the expression.
I know sum expression only with xor gate. Cannot come to this conclusion.
0
votes
1answer
43 views
Identification of line code from amplitude, phase and PSD plots
I recorded some transmitted data using the Noo-Elec RTL2832 software-defined radio. The data is transmitted at a carrier frequency of 1.3GHz and sampled at 2.4MHz. The transmitted data is a set of ...
46
votes
8answers
8k views
Why is digital serial transmission used everywhere? i.e. SATA, PCIe, USB
While looking at SATA, PCIe, USB, SD UHS-II it struck me that they are all the same: digital serial bitstream, transmitted using differential pairs (usually 8b/10b coded), with some differences in ...
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votes
1answer
128 views
How to use multiplexor 74HC4067
I am using 74hc4067 IC(Multiplexer 4:16) for the extend the gpio pins can i use that gpio pins same time or not? and any one suggest about the ic how it is used?
1
vote
1answer
38 views
Method to find Correlation for a random variable and thereby power spectral density of random signal
I'm trying really hard to understand the segment of text from a standard communication book ( Modern digital and analog communications by B P Lathi). We are trying to find the power spectral density ...
